Realize that your happiness does not have to be dependent on major achievements.
Rather, I believe (and others like Dr. Victor Frankl) that happiness should be based on having meaning in your life.
So many overachievers tell themselves:
"once I get into a good college, then I'll be happy..
once I get into a good graduate program, then I'll be happy,
once I graduate and get a good job, then I'll be happy,
once I make manager/partner/tenure, etc., then I'll be happy..."
The list goes on and on. The cycle never ends, until you want it to.
Thus, I disagree with the other posters (coming from a psychology background here, not pharmacy). It's not necessarily about setting new "goals," as it is about finding new meaning in your life left by the void of not having a major academic goal to chase after. And by meaning in life, I mean a sense of purpose how you see your life (cognitions) and how you spend your time (behaviors).
"Meaning" is not an easy or concrete thing to attain, but you'll realize that it's very different than writing a big goal on a to-do list with a date, and "checking it off" when its done. It's an organic process that develops throughout your life.
Also realize that you're very fortunate to be in a place in your life where you have the financial security and time to do some personal development and find some sort of meaning in your life. Best of luck.